Auris mileage going down, why?

[Perafelix]

I have bought a second hand Auris hybrid and during the first 2-3 months I had an average of 56mpg. Then (I have no idea why) the car started to average 48mpg!! Any reason why this could possibly happen? Nothing has changed in the car or the way I drive

[fordulike]

Weather's getting colder. I notice a drop in mpg once the temperature drops. There's a few different factors why this happens, but a Google search will reveal the answer.

[Kevin Hart]

Fordulike is right. Season has changed, it is the cause. Lots of school was on vacation during the summer. So, there's a change in traffic as well. It's all good. Don't hustle yourself.

[Perafelix]

I bought the car in April and this happened starting in July when it was still very hot. Now actually it starts to be a bit colder and is going down again to about 46mpg! Any idea what is happening?

[fordulike]

To be honest, probably nothing to worry about. I wouldn't be quibbling over 10 mpg. If it dropped down to say 36 mpg, then maybe, but 46 mpg is still good. I only achieve that out of my tiny little engined AYGO!

One thing you could check yourself, is jack each wheel up, spin the wheel and see if any are dragging.

[Sir Jestalot]

Sorry Fordulike but I disagree; a 10mpg drop is pretty serious I think if the same drive mode has been in use throughout.   I had mid-50's MPG from March through the summer months while using Eco mode almost exclusively, but I've just finished an experiment with using Normal mode for three tankfuls (someone had said there was no difference between them) and that gave high 40s MPG which is quite a difference.   My previous car (Ford Fiesta Zetec) returned between 39 and 43 MPG consistently throughout the four years I owned it.   Not a very good comparison I know, but it does show that the MPG readings should not vary by very much, and certainly less than 10.

[furtula]

Car takes longer to reach optimal temperature due to colder weather.  That means car is running more richer (using more gas) until it warms up. If you do a lot of small trips, few miles only, then the difference is more noticeable.

[Cyker]

I reckon it's the winter; Hybrids and diesels, esp. ones used for short distance trips, are known to get hit pretty hard in the mpgs as the temperature drops.

Petrol engines aren't affected so much as they naturally waste a lot of heat which helps them come up to temp faster, even in winter, but for instance by mid-winter I can get half way to work before the cold engine light goes out if I drive my D4D for maximum efficiency!

Hybrids have the same problem as they have to run the ICE more to keep it at minimum operating temp, and when it's doing that it's obviously running below optimal temp and more fuel is wasted.

 

[Gerg]

As well as all the above, the petrol engine will run an extra amount, if required, simply to generate the hot coolant needed to service the heater of the car interior.  E.g. One cold day, try driving with the heater turned down further than you normally do and see if the mpg figure goes up.

Also, at 5 years old, if your car is still using the original 12v Battery, then I'm sure some owners (sorry, no link or reference here) have noticed that as the 12v Battery slowly gets weaker, the engine is called upon more to try to charge it up (via the high voltage system).  As the battery is reluctant to achieve a 'good' charge (because it is old), therefore the engine runs more than it normally would.

The catalytic converter cooling down (because the engine is not needed at that time) may require engine operation to heat it back up, I expect that this will be monitored somehow.  If the cat. gets below, er..., 300 degrees centigrade(I can't remember exactly), then the measurable emissions when the engine does run will be very poor.  The cat. on the Auris is quite a long way from the engine, so in cold weather keeping it hot becomes a bigger problem.

[Heidfirst]

2 hours ago, Gerg said:

As well as all the above, the petrol engine will run an extra amount, if required, simply to generate the hot coolant needed to service the heater of the car interior.

& increased use of lights & rear/mirror demist.

[Duggerz]

In the UK and other EU countries the EN590 specification covers both summer and winter grades of diesel. Winter diesel contains a higher proportion of light fractions and has a lower calorific value, I.e.burns with less energy which translates to lower mpg. At some point each year I notice the switch at the pump when my mpg reduces slightly, but it's certainly not anywhere near 10 reduction, but I'm driving a much older vehicle that isn't so efficient in the first place. Short journeys will exacerbate the effect though, as already mentioned, as a diesel vehicle will run cold much longer. If you're interested this Wikipedia explains the different grades somewhat.

https://en.m.wikipedia.org/wiki/Winter_diesel_fuel

Sent from my D6603 using Tapatalk

[FROSTYBALLS]

How are you estimating the fuel consumption - calculating brim to brim or from the car's multi function display?

[Sir Jestalot]

43 minutes ago, FROSTYBALLS said:

How are you estimating the fuel consumption - calculating brim to brim or from the car's multi function display?

You didn't say who you were asking, but in my case I do both:  I do brim-to-brim and calculate the MPG that way, and I also record the car's displayed MPG (everything's recorded in an Excel spreadsheet - been doing that for the last 20 years, with ever more refinements!).  The difference between the two varies; once the difference was only 0.9 and another time it was 5.8, but the displayed figure is always the higher number (i.e the more optimistic).  I'm never sure if I really am filling to the brim, but I always let the pump click a few times before I stop refueling, so I'm not sure which figure is the most trustworthy.

[Nitro234]

You shouldn’t do that, only really brim it to one click. Fuel will get into the evap system and eventually malfunction. 

[FROSTYBALLS]

5 hours ago, FROSTYBALLS said:

How are you estimating the fuel consumption - calculating brim to brim or from the car's multi function display?

 

4 hours ago, Sir Jestalot said:

You didn't say who you were asking.

The question was to the OP.

[Sir Jestalot]

2 hours ago, Nitro234 said:

You shouldn’t do that, only really brim it to one click. Fuel will get into the evap system and eventually malfunction. 

Well, in all honesty I've been filling that way for many years and never had a problem.   Sometimes the pump cuts out early due to back pressure and/or an oversensitive pump.

 

[Cjohnston1982]

Check your tyre pressures too. Tyre pressures drop in cold weather and this increases rolling resistance. I find tyres tend to lose at least 10% in PSI between summer and winter.

[Sir Jestalot]

4 hours ago, Cjohnston1982 said:

Check your tyre pressures too. Tyre pressures drop in cold weather and this increases rolling resistance. I find tyres tend to lose at least 10% in PSI between summer and winter.

Strangely enough, the tyre pressure warning light came on on Friday in my Auris Hybrid.  I checked all the tyres and most were about 3-4 psi low (should be 33psi).  I corrected the pressure and the light went out after I'd done the last tyre. Somehow I thought they would have to be at a much lower pressure for the warning system to activate (I've never had the warning light come on before).

[Catlover]

Could the reduction in mpg partly be due to your driving style changing.  You say only had the car a few months. Could it be that initially you were trying had to get as many mpg as you could, now the "novelty" has worn off could your driving style be less conservative.   I feel thats what happened to me to some degree, although everything else that others have posted could be contributory factors.

 

[fordulike]

42 minutes ago, Catlover said:

Could the reduction in mpg partly be due to your driving style changing.  You say only had the car a few months. Could it be that initially you were trying had to get as many mpg as you could, now the "novelty" has worn off could your driving style be less conservative.   I feel thats what happened to me to some degree, although everything else that others have posted could be contributory factors.

 

Isn't Toyota's advertising slogan something like ' Drive it like you stole it ', or is it, ' Always a better way '

I can never remember which

[16_Auris_HSD]

5 hours ago, Catlover said:

Could the reduction in mpg partly be due to your driving style changing.  You say only had the car a few months. Could it be that initially you were trying had to get as many mpg as you could, now the "novelty" has worn off could your driving style be less conservative.   I feel thats what happened to me to some degree, although everything else that others have posted could be contributory factors.

 

That's what's happened to me too. And I'm somewhat taken aback by how the numbers have changed since I stopped trying too hard and instead just go with the flow of traffic. There's no regularity, one time I'll get low 40's then driving in similar conditions I'd get mid 50's. 30's happen too. The average dropped slightly too but is still at 52 though which boosts my ego somewhat.

[Sir Jestalot]

18 hours ago, 16_Auris_HSD said:

That's what's happened to me too. And I'm somewhat taken aback by how the numbers have changed since I stopped trying too hard and instead just go with the flow of traffic. There's no regularity, one time I'll get low 40's then driving in similar conditions I'd get mid 50's. 30's happen too. The average dropped slightly too but is still at 52 though which boosts my ego somewhat.

I think I have probably also been a bit too obsessive over MPG.  When all's said and done I'm getting much better fuel economy than I've ever had with any previous cars, and from a 1.8L engine to boot (my previous car - Fiesta - had a 1.4L engine).   Not to mention zero road tax into the bargain.   So maybe I should just go with the flow myself :-)

[furtula]

The MPG you guys are getting is pretty good, compared to other cars with such engines / weight.  As the post above says, dont stress it, and just drive as you would normally do.

When i reset my counter, and did a few short drives where car barely had time to heat up, i was getting 23 MPG. Reset it again, did a 20 + 20 (after 1 hr sitting) drive in traffic, car warmed up decently, got 45 mpg.

 

[Sir Jestalot]

5 hours ago, furtula said:

The MPG you guys are getting is pretty good, compared to other cars with such engines / weight.  As the post above says, dont stress it, and just drive as you would normally do.

When i reset my counter, and did a few short drives where car barely had time to heat up, i was getting 23 MPG. Reset it again, did a 20 + 20 (after 1 hr sitting) drive in traffic, car warmed up decently, got 45 mpg.

 

My usual habit is to reset my MPG reading and also the Trip A counter at each refill.   The MPG reading rises and falls quite rapidly at first but settles down after about 50 miles.

A lot of my trips are quite short and/or not often at a high speed, so the engine cuts in and out a lot, and I do wonder if the engine (or rather its oil) ever heats up enough.   I've always considered short trips to be an engine's enemy because of moisture condensing into the engine oil.  I do do a weekly 60-mile round trip (with an hour's stop in between) so hopefully that helps, but I wonder if it would benefit the engine if I had the oil changed twice a year rather than annually.

[Grandprix]

Had a similar problem my car was called in for recall  to do software update taking it easy I could get high 60s on a run highest was 74mpg since update 56/62 seems to be average contacted dealer and Toyota and they can't understand why this has happened